1. Field of the Invention
The present invention relates to a resin pipe wherein a multilayer pipe, including a barrier layer, is extruded simultaneously and wherein a corrugated part is formed, and to a resin molded component.
2. Description of the Related Art
Conventionally, when the type of resin pipe has been applied to piping for fuel, such as an inlet pipe, a barrier layer that has excellent resistance to fuel permeation has been interposed in order to reduce the amount of fuel vapor that escapes to the outside. The provision of a corrugated part to facilitate bending along the filling pathway is known in this type of inlet pipe (for example, JP-A-7-217776). FIG. 9 is a cross-sectional view showing the vicinity of the corrugated part of a conventional resin pipe. A resin pipe 100 comprises a flow path 100a and the multiple layers of an inner layer 102, a barrier layer 104, and an outer layer 106, where peaks 110a and valleys 110b form the corrugated part 110. This type of resin pipe 100 may be manufactured using a blow molding method or a corrugation fabrication method. The blow molding method is a method wherein a multilayer parison is blown to use a die to shape the parison into a corrugated shape, and the corrugation molding method is a method wherein shaping is done into a corrugated shape using a die that is moved in a looped path as a multilayer extruded pipe body is extruded.
However, in this type of molding process, when shaping into a corrugated part 110, the thickness of the barrier layer 104 in the corrugated part 110 falls to less than 50% of the thickness in the straight part because the barrier layer 104 is also elongated along the molding surface of the die, and the surface area of the barrier layer 104 is also expanded. This has a negative effect on the resistance to fuel permeation, proportional to the reduction in wall thickness and proportional to the increase in surface area. Because of this, it is necessary in the corrugated part 110 to provide a thickness in the barrier layer 104 that anticipates thinning of the corrugated part 110, which increases the amount of the expensive barrier layer 104 material that is used, increasing costs.